Compressor

ABSTRACT

In a compressor provided with two compression mechanisms of a rotary type compression mechanism and a scroll type compression mechanism, torque fluctuations are reduced. The compressor  1  includes a hermetic housing  2 , a low stage-side compression mechanism  3  and a high stage-side compression mechanism  4  provided in the hermetic housing  2 ; and an electric motor  21  for driving the low stage-side compression mechanism  3  and the high stage-side compression mechanism  4 . The low stage-side compression mechanism  3  is a rotary type compression mechanism, and the high stage-side compression mechanism  4  is a scroll type compression mechanism. The suction shutoff of the scroll type compression mechanism is accomplished when a rotor  34  of the rotary type compression mechanism is at a position A corresponding to the bottom dead center, at a position B of being rotated through 90 degrees from the bottom dead center, or between the positions A and B.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a compressor and, more particularly, toa technique for restraining torque fluctuations of a compressor providedwith two compression mechanisms of a rotary type compression mechanismand a scroll type compression mechanism.

2. Description of the Related Art

A compressor provided with two compression mechanisms of a rotary typecompression mechanism and a scroll type compression mechanism has beenproposed. For example, Japanese Patent Laid-Open No. 5-87074 discloses atwo-stage compressor in which an electric motor is provided in a singlehermetic housing and two compression mechanisms each driven by therotating shaft of the electric motor are provided; one of these twocompression mechanisms is made a rotary type compression mechanism andthe other thereof is made a scroll type compression mechanism; and oneof the two compression mechanisms is on the low stage side and the otherthereof is on the high stage side. Japanese Patent Laid-Open No. 5-87074describes that in this two-stage compressor, the low stage-sidecompression mechanism is preferably of a rotary type. According to thistwo-stage compressor, the low stage-side compressor compresses gasesfrom a low pressure to an intermediate pressure, and the high stage-sidecompressor compresses gases from the intermediate pressure to a highpressure. Therefore, the drawback of individual compressor is overcome,and a compressor small in size but high in performance can be providedas compared with the case where a rotary type compression mechanism or ascroll type compression mechanism is used singly to compress gases froma lower pressure to a high pressure.

To restrain vibrations from occurring, it is desirable that thecompressor generate small torque fluctuations. The rotary typecompression mechanism generates larger torque fluctuations than thescroll type compression mechanism. Japanese Patent Laid-Open No. 5-87074describes that, by combining the rotary type compression mechanism withthe scroll type compression mechanism, the compression ratio can bedecreased, so that the torque fluctuations in the rotary typecompression mechanism can be reduced. However, a further reduction intorque fluctuations is desired.

SUMMARY OF THE INVENTION

The present invention has been accomplished to solve the above technicalproblem, and accordingly an object thereof is to reduce torquefluctuations of a compressor provided with two compression mechanisms ofa rotary type compression mechanism and a scroll type compressionmechanism.

To achieve the above object, the inventors studied the behavior oftorque fluctuations in a rotary type compression mechanism and a scrolltype compression mechanism. The study results are shown in FIGS. 12 and13. FIG. 12 is a graph showing the relationship between the rotationangle β (abscissa) of a rotor of the rotary type compression mechanismand the torque T (ordinate), and FIG. 13 is a graph showing therelationship between the rotation angle β (abscissa) of an orbitingscroll of the scroll type compression mechanism and the torque T(ordinate). From FIGS. 12 and 13, it can be seen that the rotary typecompression mechanism generates larger torque fluctuations compared withthose generated by the scroll type compression mechanism. The compressorprovided with two compression mechanisms of the rotary type compressionmechanism and the scroll type compression mechanism generates torque ofthe sum of the torque in the rotary type compression mechanism and thetorque in the scroll type compression mechanism (total torque).Therefore, torque fluctuations larger than the torque fluctuations inthe rotary type compression mechanism only may be generated in thecompressor provided with the two compression mechanisms. On the otherhand, as shown in FIG. 13, for the scroll type compression mechanism,although a region in which the torque T is relatively large is present,a region in which the torque T is relatively small is also present.Therefore, there is a possibility that the fluctuations in total torquecan be made smaller than the torque fluctuations in the rotary typecompression mechanism only. Accordingly, the inventors observed thefluctuations in total torque by variously changing the positionalrelationship between the rotary type compression mechanism and thescroll type compression mechanism in the direction of rotation. As theresult, the inventors found that in the case where the rotary typecompression mechanism and the scroll type compression mechanism have aspecific positional relationship, the fluctuations in total torque canbe made smaller than the torque fluctuations in the rotary typecompression mechanism only.

The compressor in accordance with the present invention made based onthe above-described study result includes a hermetic housing; a lowstage-side compression mechanism and a high stage-side compressionmechanism provided in the hermetic housing; and an electric motor fordriving the low stage-side compression mechanism and the high stage-sidecompression mechanism, one of the low stage-side compression mechanismand the high stage-side compression mechanism being a rotary typecompression mechanism, and the other thereof being a scroll typecompression mechanism. In this compressor, the rotary type compressionmechanism has a rotor and a blade reciprocating between the top deadcenter of the blade and the bottom dead center of the blade with therotation of the rotor while the tip end of the blade is in contact withthe rotor; and the suction shutoff of the scroll type compressionmechanism is accomplished when the rotor is at a position Acorresponding to the bottom dead center, at a position B of beingrotated through 90 degrees from the position corresponding to the bottomdead center, or between the positions A and B.

Also, in the case of a two-cylinder rotary type compression mechanism,the suction shutoff of the scroll type compression mechanism isaccomplished when the rotor is at a position C of being rotated through−80 degrees from the position corresponding to the bottom dead center,at a position D of being rotated through −100 degrees from the positioncorresponding to the bottom dead center, or between the positions C andD, or at a position E of being rotated through 80 degrees from theposition corresponding to the bottom dead center, at a position F ofbeing rotated through 100 degrees from the position corresponding to thebottom dead center, or between the positions E and F. Thereby, thefluctuations in total torque can be made small.

In the case where the low stage-side compression mechanism is configuredby the rotary type compression mechanism, and the high stage-sidecompression mechanism is configured by the scroll type compressionmechanism; and the scroll type compression mechanism has a capacitycontrol mechanism including an exhaust port for refrigerant gas, thesuction shutoff is accomplished when the exhaust port is closed by theorbiting scroll of the scroll type compression mechanism.

Torque fluctuations especially pose a problem when the compressor isoperated at a low speed, that is, when the compressor is operated whileusing the capacity control mechanism. For this reason, in the case ofthe compressor having a capacity control function, the closure of theexhaust port accomplished by the orbiting scroll of the scroll typecompression mechanism is regarded as the suction shutoff in the presentinvention.

According to the present invention, by incorporating the rotary typecompression mechanism and the scroll type compression mechanism in thecompressor so as to provide a specific positional relationship, thefluctuation amount of total torque can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a construction of a compressor towhich the present invention is applied;

FIG. 2 is a plan view showing a construction of a low stage-sidecompression mechanism (rotary type compression mechanism);

FIG. 3 is a view showing an engagement state of a fixed scroll wrap andan orbiting scroll wrap at timing at which an orbiting scroll isrevolved to form a closed compression chamber together with a fixedscroll;

FIGS. 4A to 4D are graphs showing the relationship between a shift angleα between blade bottom dead center and scroll suction shutoff and atorque fluctuation amount;

FIG. 5 is a graph showing the relationship between a shift angle α of 0to 360 degrees (−360 degrees) and a difference between the maximum valueTmax and the minimum value Tmin of total torque (Tmax−Tmin);

FIG. 6 is a schematic view showing the relationship between a rotorposition and suction shutoff timing;

FIG. 7 is a sectional view showing a portion near a scroll typecompression mechanism of a compressor provided with a capacity controlmechanism;

FIGS. 8A and 8B are views showing an engagement state of a fixed scrollwrap and an orbiting scroll wrap in a scroll type compression mechanismof a compressor provided with a capacity control mechanism;

FIG. 9 is a sectional view showing a twin rotary type compressionmechanism;

FIGS. 10A to 10D are graphs showing the relationship between a shiftangle α between blade bottom dead center and scroll suction shutoff anda torque fluctuation amount in the case where a twin rotary typecompression mechanism is provided;

FIG. 11 is a graph showing the relationship between a shift angle α of 0to 360 degrees (−360 degrees) and a difference between the maximum valueTmax and the minimum value Tmin of total torque (Tmax−Tmin) in the casewhere a twin rotary type compression mechanism is provided;

FIG. 12 is a graph showing the relationship between the rotation angleof a rotor of a rotary type compression mechanism and the occurringtorque; and

FIG. 13 is a graph showing the relationship between the rotation angleof an orbiting scroll of a scroll type compression mechanism and theoccurring torque.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be described in detailwith reference to the accompanying drawings.

FIG. 1 is a sectional view showing the construction of a compressor 1 inthis embodiment.

In the compressor 1, a low stage-side compression mechanism 3 isprovided in the lower part of a hermetic housing 2, and a highstage-side compression mechanism 4 is provided in the upper parttherein. Also, in the central part of the hermetic housing 2, anelectric motor 21 is provided between the low stage-side compressionmechanism 3 and the high stage-side compression mechanism 4. Theelectric motor 21 includes a stator 22 and a rotor 23. The rotor 23 isintegrally connected with a crankshaft 24. The lower end part of thecrankshaft 24 forms a crankshaft 25 for the low stage-side compressionmechanism 3, and the upper end part thereof forms a crankshaft 26 forthe high stage-side compression mechanism 4. Also, in the bottom part ofthe hermetic housing 2, a predetermined amount of lubricating oil 27 isstored. The lubricating oil 27 is fed to predetermined lubricationlocations of the low stage-side compression mechanism 3 and the highstage-side compression mechanism 4 via an oil feeding hole 11 formed inthe axial direction of the crankshaft 24 by a positive displacementlubrication pump 28 provided in the lower end part of the crankshaft 25.

The low stage-side compression mechanism 3 is configured by a rotarytype compression mechanism. As the low stage-side compression mechanism3, a general rotary type compression mechanism is used which has acylinder chamber 31, and includes a cylinder body 30 fixed to thehermetic housing 2, an upper bearing 32 and a lower bearing 33 providedon top of and beneath the cylinder body 30, respectively, a rotor 34fitted in a crank part 25A of the crankshaft 25 and rotated slidingly inthe cylinder chamber 31, a discharge cover 36 forming a discharge cavity35, and a blade 38 (refer to FIG. 2) partitioning the cylinder chamber31. As shown in FIG. 2, the blade 38 is disposed in a slit 39 formed inthe cylinder body 30. The slit 39 is formed along the radial directionof the cylinder body 30 so as to have an approximately uniform width,and one end thereof is open to the cylinder chamber 31. At the other endof the slit 39, a spring S is disposed to press the blade 38 toward therotor 34. The blade 38 reciprocates along the radial direction with therotation of the rotor 34 while the tip end thereof is in contact withthe outer periphery of the rotor 34. The state in which the tip end ofthe blade 38 projects farthest in the cylinder chamber 31 is referred toas a bottom dead center, and the state in which the whole of the blade38 is present within the slit 39 is referred to as a top dead center.

In the low stage-side compression mechanism 3, refrigerant gas suckedinto the cylinder chamber 31 via a suction pipe 37 connected to anaccumulator, not shown, is compressed to an intermediate pressure by therotation of the rotor 34, and then is discharged into the dischargecavity 35 and is further discharged into the hermetic housing 2 througha discharge opening provided in the discharge cover 36.

The refrigerant gas having the intermediate pressure discharged into thehermetic housing 2 flows into an upper space of the hermetic housing 2through an air gap and the like of the electric motor 21, and is suckedinto the high stage-side compression mechanism 4.

The high stage-side compression mechanism 4 is configured by a scrolltype compression mechanism.

The high stage-side compression mechanism 4 includes a bearing 40 havinga bearing part 41 for supporting the crankshaft 26 from the outerperiphery thereof and a fixing plate 42 for fixing the bearing 40. Thefixing plate 42 is fixed to the hermetic housing 2.

Also, the high stage-side compression mechanism 4 includes a fixedscroll 43 and an orbiting scroll 44 for forming a pair of compressionchambers 45 by being engaged with each other with the phase beingshifted, a drive bush 46 that connects the orbiting scroll 44 to a crankpin part 26A formed at the shaft end of the crankshaft 26 to revolve theorbiting scroll 44, and an Oldham's ring 47 provided between theorbiting scroll 44 and the bearing 40 to revolve the orbiting scroll 44while preventing the rotation thereof.

Further, the high stage-side compression mechanism 4 includes adischarge valve 48 provided on the back surface of the fixed scroll 43and a discharge cover 50 fixed on the back surface of the fixed scroll43 to form a discharge chamber 49 between the discharge cover 50 and thefixed scroll 43.

In the high stage-side compression mechanism 4, a discharge pipe 51 isconnected to the discharge chamber 49, so that the refrigerant gashaving been compressed to high temperature and pressure by the proceduredescribed below is discharged to the outside of the compressor 1.

In the high stage-side compression mechanism 4, the refrigerant gashaving been compressed to the intermediate pressure by the lowstage-side compression mechanism 3 and discharged into the hermetichousing 2 is sucked into the paired compression chambers 45 through asuction opening 52. The paired compression chambers 45 are moved to thecenter side while the volume thereof is decreased by the revolution ofthe orbiting scroll 44, and join together to form one compressionchamber 45. During this time, the refrigerant gas is compressed from theintermediate pressure to a high pressure (discharge pressure), and isdischarged into the discharge chamber 49 through a discharge port 53formed in the central part of the fixed scroll 43. This high temperatureand pressure refrigerant gas is discharged to the outside of thecompressor 1 via the discharge pipe 51.

The operation of the compressor 1 constructed as described above isexplained.

In the low stage-side compression mechanism 3, a refrigerant gas havinga low pressure is sucked into the cylinder chamber 31 from theaccumulator, not shown, via the suction pipe 37. This refrigerant gas iscompressed to the intermediate pressure by the rotation of the rotor 34made via the electric motor 21 and the crankshaft 25, and then isdischarged into the discharge cavity 35. The refrigerant gas is furtherdischarged from the discharge cavity 35 into the hermetic housing 2through the discharge opening provided in the discharge cover 36.Thereby, the interior of the hermetic housing 2 is made to have anintermediate-pressure atmosphere, and therefore the electric motor 21and the lubricating oil 27 are made to have a temperature equivalent tothat of the intermediate-pressure refrigerant gas.

The above-mentioned intermediate-pressure refrigerant gas is sucked intothe compression chambers 45 of the high stage-side compression mechanism4 through the suction opening 52 that is open to the hermetic housing 2.In the high stage-side compression mechanism 4, the electric motor 21 isdriven, and thereby the orbiting scroll 44 is revolved with respect tothe fixed scroll 43 via the crankshaft 26, the crank pin part 26A, andthe drive bush 46, by which the refrigerant gas is compressed. Thereby,the intermediate-pressure refrigerant gas is compressed to ahigh-pressure state, and is discharged into the discharge chamber 49through the discharge valve 48.

The high temperature and pressure refrigerant gas discharged into thedischarge chamber 49 is discharged from the compressor 1 through thedischarge pipe 51 connected to the discharge chamber 49.

FIG. 3 is a view showing an engagement state of a wrap 43L of the fixedscroll 43 and a wrap 44L of the orbiting scroll 44 at timing at whichthe orbiting scroll 44 and the fixed scroll 43 form the closedcompression chambers 45. Before this timing, the compression chambers 45are open, so that the refrigerant gas is sucked. However, after thistiming, a tip end part 43E of the fixed scroll 43 comes into contactwith the outer periphery of the orbiting scroll 44, and a tip end part44E of the orbiting scroll 44 comes into contact with the outerperiphery of the fixed scroll 43, by which the suction of therefrigerant gas is stopped. This state is referred to as a suctionshutoff.

The inventors determined the relationship between shift angle α andtorque fluctuation amount in the compressor 1 constructed as describedabove. Some results are shown in FIG. 4. Herein, the shift angle α isdefined as described below. When the blade 38 is in a state of bottomdead center in the rotary type compression mechanism and a suctionshutoff state is formed in the scroll type compression mechanism, theshift angle α between the rotary type compression mechanism and thescroll type compression mechanism is 0 degree. Also, when suctionshutoff is accomplished in the scroll type compression mechanism at aposition at which the rotor 34 rotates through 90 degrees from theposition corresponding to the bottom dead center, the shift angle αbecomes 90 degrees.

FIGS. 4A to 4D are graphs in which the abscissas represent the rotationangle β of the rotary type compression mechanism and the scroll typecompression mechanism, and the ordinates represent torque T. FIGS. 4A to4D show results when the shift angle α is 0 degree, 90 degrees, 180degrees, and 270 degrees, respectively. Also, in FIGS. 4A to 4D, thechain line (alternate long and short dash line) indicates the torque Tof the rotary type compression mechanism only, the dotted line indicatesthe torque T of the scroll type compression mechanism only, and thesolid line indicates the total of the torque T of the rotary typecompression mechanism and the torque T of the scroll type compressionmechanism.

As shown in FIGS. 4A to 4D, in both of the rotary type compressionmechanism and the scroll type compression mechanism, the torque Tfluctuates according to the rotation angle β, and in particular, thetorque of the rotary type compression mechanism fluctuates greatly.Also, from FIGS. 4A to 4D, it can be seen that the fluctuation amount oftotal torque differs depending on the shift angle α. Since this totaltorque is applied to the crankshaft 24 of the compressor 1, the torquefluctuations indicated by the solid line is desired to be small.Therefore, a difference between the maximum value Tmax and the minimumvalue Tmin of the total torque indicated by the solid line (Tmax−Tmin)was determined in the range of the shift angle α of 0 to 360 degrees(−360 degrees). The result is shown in FIG. 5. For the rotation angle βin the rotary type compression mechanism, the position of the rotor 34at the time when the blade 38 is at the top dead center is set at 0degree.

From FIG. 5, it can be seen that the torque fluctuation amount can bemade small in the range of the shift angle α of 0 to 90 degrees. This isbecause a portion in which the torque T of the rotary type compressionmechanism is large and a portion in which the torque T of the scrolltype compression mechanism is small are canceled each other. Based onthis result, as shown in FIG. 6, in the present invention, the rotarytype compression mechanism and the scroll type compression mechanism arefixed to the crankshaft 24 (25, 26) so that the suction shutoff ofscroll type compression mechanism is accomplished when the rotor 34 isat a position A corresponding to the bottom dead center of the blade 38,at a position B of being rotated through 90 degrees from the positioncorresponding to the bottom dead center, or between the positions A andB. By adopting this configuration, the torque fluctuation amount of thecompressor 1 can be made small.

Also, by adopting this configuration, noise generated from thecompressor 1 can be reduced. That is to say, in the rotary typecompression mechanism, loudest noise is generated when the blade 38comes to the top dead center (rotation angle 0 degree). This is causedby the closure of a discharge valve (not shown) of the rotary typecompression mechanism. Also, in the scroll type compression mechanism,loud noise is generated at the suction shutoff time. This is because thefixed scroll 43 and the orbiting scroll 44 come into contact with eachother. Therefore, if the suction shutoff is accomplished in the scrolltype compression mechanism when the blade 38 comes to the top deadcenter in the rotary type compression mechanism, the generated noisebecomes remarkable. However, in the compressor 1, the suction shutoff isnot accomplished in the scroll type compression mechanism when the blade38 comes to the top dead center in the rotary type compressionmechanism. Therefore, the compressor 1 is effective in reducing noise.

Further, the discharge timing of refrigerant gas in the rotary typecompression mechanism is in the range from the vicinity of 180 degreesof the rotation angle β (corresponding to the bottom dead center) to 360degrees thereof. By adopting the above-described configuration, thescroll type compression mechanism can suck refrigerant gas dischargedfrom the rotary type compression mechanism, so that degradation inperformance caused by pressure pulsation can be restrained.

Capacity control is sometimes carried out according to the operationstatus of refrigeration system, air conditioner, or the like. Forexample, in the case of refrigeration system, in the operation status inwhich the refrigerated state is maintained, the load of the scroll typecompression mechanism decreases considerably as compared with theoperation status in which goods are cooled to a desired temperature andrefrigerated. Therefore, at the time of low-load operation, capacitycontrol is sometimes carried out. Specifically, the discharge rate fromthe discharge port is controlled by drawing the refrigerant gas beingcompressed from the compression chamber. The drawn refrigerant gas issupplied again to the suction side of the scroll type compressionmechanism.

FIG. 7 is a sectional view showing a portion near the scroll typecompression mechanism of a compressor 100 provided with a capacitycontrol mechanism. Like the compressor 1, the compressor 100 includesthe low stage-side compression mechanism 3 which is a rotary typecompression mechanism and the like. As shown in FIG. 7, the fixed scroll43 is formed with an exhaust port 60 for capacity control. Correspondingto this exhaust port 60, a check valve 61 is disposed on the backsurface of the fixed scroll 43. At the time of capacity control, therefrigerant gas in a process of being compressed in the compressionchamber 45 is exhausted via the exhaust port 60, the check valve 61, anda capacity control pipe 62. In FIG. 7, the same symbols as those in FIG.1 denote the same elements as those of the compressor 1 shown in FIG. 1.

In the case of the compressor 100 provided with the above-describedcapacity control function, at the time of suction shutoff in thecompressor 1, since the exhaust port 60 communicates with thecompression chamber 45 as shown in FIG. 8A, substantially, the suctionshutoff is not achieved. When the revolution of the orbiting scroll 44proceeds, the exhaust port 60 is closed by a wrap vertex part of theorbiting scroll 44 as shown in FIG. 8B. The suction shutoff in thecompressor 100 having the capacity control function is accomplished atthe timing at which the exhaust port 60 is closed. Torque fluctuationspose a problem especially when the compressor 100 is operated at a lowspeed, that is, when the compressor 100 is operated while the capacitycontrol is carried out. For this reason, the suction shutoff in thecompressor 100 having the capacity control function is accomplished atthe timing at which the exhaust port 60 is closed.

As the compressor 1 shown in FIG. 1, an example in which the rotary typecompression mechanism has a single cylinder (single rotary) has beenshown. However, the present invention can be applied to a compressor 200in which the rotary type compression mechanism is configured so as tohave two cylinders (twin rotary) as shown in FIG. 9 and other portionsare configured as those of the compressor 1 shown in FIG. 1. The twinrotary is provided with two cylinder bodies 30 a and 30 b, and thecylinder body 30 a has a cylinder chamber 31 a and the cylinder body 30b has a cylinder chamber 31 b. In the cylinder chamber 31 a, a rotor 34a is disposed, and in the cylinder chamber 31 b, a rotor 34 b isdisposed. The refrigerant gas sucked into the cylinder chambers 31 a and31 b via suction pipes 37 a and 37 b connected to the accumulator,respectively, is compressed by the rotations of the rotors 34 a and 34b. A mechanism having the cylinder body 30 a is referred to as a firstrotary, and a mechanism having the cylinder body 30 b is referred to asa second rotary. The same symbols as those in FIG. 1 denote the sameelements as those of the compressor 1 shown in FIG. 1.

Although not shown in the figure, the blade (38) is disposed in both ofthe first rotary and the second rotary. When the blade of the firstrotary is at the bottom dead center, the blade of the second rotary isat the top dead center. Also, when the blade of the first rotary is atthe top dead center, the blade of the second rotary is at the bottomdead center. That is, the blades of the first rotary and the secondrotary are 180 degrees out of phase.

For the compressor 200 provided with the first rotary and the secondrotary as described above, the relationship between the shift angle αand the torque fluctuations was determined. The results are shown inFIG. 10. FIGS. 10A to 10D are graphs in which the abscissas representthe rotation angle β of the rotary type compression mechanism and thescroll type compression mechanism, and the ordinates represent torque T.FIGS. 10A to 10D show results when the shift angle α is 0 degree, 90degrees, 180 degrees, and 270 degrees, respectively. Also, in FIGS. 10Ato 10D, the chain line (alternate long and short dash line) indicatesthe torque T of the rotary type compression mechanism (twin rotary)only, the dotted line indicates the torque T of the scroll typecompression mechanism only, and the solid line indicates the total ofthe torque T of the rotary type compression mechanism and the torque Tof the scroll type compression mechanism.

From FIGS. 10A to 10D, it can be seen that the fluctuation amount oftotal torque differs depending on the shift angle α. Therefore, adifference between the maximum value Tmax and the minimum value Tmin ofthe total torque indicated by the solid line (Tmax−Tmin) was determinedin the range of the shift angle α of 0 to 360 degrees (−360 degrees).The result is shown in FIG. 11.

As shown in FIG. 11, at the shift angle α of −80 degrees to −100 degreesor 80 degrees to 100 degrees, the torque difference Tmax−Tmin is small.Therefore, in the case of the twin rotary, the rotary type compressionmechanism and the scroll type compression mechanism are fixed to thecrankshaft 24 (25, 26) so that the suction shutoff of scroll typecompression mechanism is accomplished when the rotor is at a position Cof being rotated through −80 degrees from the position corresponding tothe bottom dead center, at a position D of being rotated through −100degrees from the position corresponding to the bottom dead center, orbetween the positions C and D, or at a position E of being rotatedthrough 80 degrees from the position corresponding to the bottom deadcenter, at a position F of being rotated through 100 degrees from theposition corresponding to the bottom dead center, or between thepositions E and F.

The above is an explanation of the embodiment of the present invention.The present invention is not limited to the above-described embodiment,and changes can be made appropriately without departing from the spiritand scope of the present invention. For example, in the above-describedembodiment, a rotary type compression mechanism is used as the lowstage-side compression mechanism 3, and a scroll type compressionmechanism is used as the high stage-side compression mechanism 4.However, this configuration can be reversed.

1. A compressor comprising: a hermetic housing; a low stage-sidecompression mechanism and a high stage-side compression mechanismprovided in the hermetic housing; and an electric motor for driving thelow stage-side compression mechanism and the high stage-side compressionmechanism, one of the low stage-side compression mechanism and the highstage-side compression mechanism being a rotary type compressionmechanism, and the other thereof being a scroll type compressionmechanism, wherein the rotary type compression mechanism has a rotor anda blade reciprocating between a top dead center of the blade and abottom dead center of the blade with the rotation of the rotor while thetip end thereof is in contact with the rotor; and a suction shutoff ofthe scroll type compression mechanism is accomplished when the rotor isat a position A corresponding to the bottom dead center, at a position Bof being rotated through 90 degrees from the position corresponding tothe bottom dead center, or between the positions A and B.
 2. Thecompressor according to claim 1, wherein the rotary type compressormechanism has a single cylinder.
 3. The compressor according to claim 1,wherein the low stage-side compression mechanism is configured by therotary type compression mechanism, and the high stage-side compressionmechanism is configured by the scroll type compression mechanism.
 4. Thecompressor according to claim 3, wherein the scroll type compressionmechanism has a capacity control mechanism including an exhaust port forrefrigerant gas, and the suction shutoff is accomplished when theexhaust port is closed by an orbiting scroll of the scroll typecompression mechanism.
 5. The compressor according to claim 4, whereinthe capacity control mechanism includes at least two exhaust ports.
 6. Acompressor comprising: a hermetic housing; a low stage-side compressionmechanism and a high stage-side compression mechanism provided in thehermetic housing; and an electric motor for driving the low stage-sidecompression mechanism and the high stage-side compression mechanism, oneof the low stage-side compression mechanism and the high stage-sidecompression mechanism being a two-cylinder rotary type compressionmechanism, and the other thereof being a scroll type compressionmechanism, wherein the rotary type compression mechanism has a rotor anda blade reciprocating between a top dead center and a bottom dead centerwith the rotation of the rotor while the tip end thereof is in contactwith the rotor; and a suction shutoff of the scroll type compressionmechanism is accomplished when the rotor is at a position C of beingrotated through −80 degrees from a position corresponding to the bottomdead center, at a position D of being rotated through −100 degrees fromthe position corresponding to the bottom dead center, or between thepositions C and D, or at a position E of being rotated through 80degrees from the position corresponding to the bottom dead center, at aposition F of being rotated through 100 degrees from the positioncorresponding to the bottom dead center, or between the positions E andF′.
 7. The compressor according to claim 6, wherein the low stage-sidecompression mechanism is configured by the rotary type compressionmechanism, and the high stage-side compression mechanism is configuredby the scroll type compression mechanism.
 8. The compressor according toclaim 7, wherein the scroll type compression mechanism has a capacitycontrol mechanism including an exhaust port for refrigerant gas; and thesuction shutoff is accomplished when the exhaust port is closed by anorbiting scroll of the scroll type compression mechanism.